Research will be conducted with human volunteers involving study of an experimental analogue of non-opiate drug abuse. Within a residential research setting volunteer drug abusers will be permitted to self- administer various sedative and stimulant compounds (barbiturates, benzodiazepines, amphetamine, cocaine) under experimentally controlled conditions. The approach and techniques of the experimental analysis of behavior will be utilized to identify and study factors which act as controlling variables of such human drug self-administration. The aim will be to identify behavioral and environmental factors which can be manipulated to control, modify and reduce drug intake. The results will contribute to improved understanding of and treatment procedures for non-opiate drug abuse.